Boron coatings of metals enhance ability to combat wear, corrosion and oxidation even at elevated temperatures. Such coatings also provide lower friction on a substrate. Wear results from impact or surface-to-surface contact and is generally comprised of: abrasion, erosion, surface fatigue and adhesion. Abrasion is the wearing away of surfaces by rubbing, grinding and other types of friction. It generally occurs when a harder material strikes a softer material and can be caused by the scouring action of sand, gravel, slag or other gritty substances. Erosion (and cavitation) is the wearing away or destruction of metals and other materials by the abrasive action of water, steam or slurries that carry abrasive materials. Pump parts are particularly subject to erosion.
Surface fatigue is the removal of surface particles arising from cyclic stress variations and includes: pitting (formation of small sharp cavities in a surface), spalling (the spontaneous chipping, fragmentation or separation of a surface or surface coating), and impact wear (the striking of one object against another—the battering, pounding type of wear that breaks, splits or deforms metal surfaces.)
Adhesion wear is the breakdown of the bonding between contacting solid surfaces leading to material transfer between the two surfaces or loss from either surface; it includes fretting (wear between tight-fitting surfaces subjected to cyclic relative motion of extremely small amplitude), and galling (severe form of adhesive wear; scuffing and scoring are terms used to describe this surface damage under lubricated conditions.)
While boron coatings of metal substrates are known, few commercially viable methods are known for boronization, especially for titanium and titanium alloys. The currently known methods of plasma-assisted, laser, and fluidized bed reactor boronizing are inadequate to achieve the attributes necessary to make them effective for use in medical implants. Still further, methods are needed which are inexpensive to carry out and are of better quality than currently known in the art.